#php editor Baicao discovered a common goroutine leak when solving programming problems. When we try to use `ReadAll(response.Body)`, the returned `response` object is returned by the `client.Do(...)` method of the `http` package. However, this operation can lead to goroutine leakage problems. In order to avoid this happening, we need to take some measures to properly handle http responses.
The question comes from a very common scenario where all bytes are read from the response body after an http method call.
With the help of https://github.com/uber-go/goleak, I discovered an interesting goroutine leak.
To demonstrate the issue, run the following test code usinggo test, which results infound an unexpected goroutine:
package main import ( "io" "net/http" "testing" "go.uber.org/goleak" "gotest.tools/v3/assert" ) func testleak(t *testing.t) { defer goleak.verifynone(t) request, err := http.newrequest(http.methodget, "https://google.com", nil) assert.nilerror(t, err) client := http.client{} response, err := client.do(request) assert.nilerror(t, err) defer response.body.close() _, err = io.readall(response.body) assert.nilerror(t, err) }
Full test output:
$ go test --- FAIL: TestLeak (1.26s) main_test.go:28: found unexpected goroutines: [Goroutine 14 in state IO wait, with internal/poll.runtime_pollWait on top of the stack: goroutine 14 [IO wait]: internal/poll.runtime_pollWait(0x7f945c1e0398, 0x72) /home/wxh/.local/go/src/runtime/netpoll.go:305 +0x89 internal/poll.(*pollDesc).wait(0xc000154280?, 0xc0000ca000?, 0x0) /home/wxh/.local/go/src/internal/poll/fd_poll_runtime.go:84 +0x32 internal/poll.(*pollDesc).waitRead(...) /home/wxh/.local/go/src/internal/poll/fd_poll_runtime.go:89 internal/poll.(*FD).Read(0xc000154280, {0xc0000ca000, 0x2000, 0x2000}) /home/wxh/.local/go/src/internal/poll/fd_unix.go:167 +0x25a net.(*netFD).Read(0xc000154280, {0xc0000ca000?, 0xc00017edd8?, 0xc0004d5808?}) /home/wxh/.local/go/src/net/fd_posix.go:55 +0x29 net.(*conn).Read(0xc00009c000, {0xc0000ca000?, 0xc0000c68f0?, 0x2c?}) /home/wxh/.local/go/src/net/net.go:183 +0x45 crypto/tls.(*atLeastReader).Read(0xc0002d4138, {0xc0000ca000?, 0x0?, 0x29f6540f238f2947?}) /home/wxh/.local/go/src/crypto/tls/conn.go:787 +0x3d bytes.(*Buffer).ReadFrom(0xc0000a0278, {0x7c3860, 0xc0002d4138}) /home/wxh/.local/go/src/bytes/buffer.go:202 +0x98 crypto/tls.(*Conn).readFromUntil(0xc0000a0000, {0x7c3b80?, 0xc00009c000}, 0xc0000a41c0?) /home/wxh/.local/go/src/crypto/tls/conn.go:809 +0xe5 crypto/tls.(*Conn).readRecordOrCCS(0xc0000a0000, 0x0) /home/wxh/.local/go/src/crypto/tls/conn.go:616 +0x116 crypto/tls.(*Conn).readRecord(...) /home/wxh/.local/go/src/crypto/tls/conn.go:582 crypto/tls.(*Conn).Read(0xc0000a0000, {0xc0001cf000, 0x1000, 0x11?}) /home/wxh/.local/go/src/crypto/tls/conn.go:1287 +0x16f bufio.(*Reader).Read(0xc0001af1a0, {0xc0001aad60, 0x9, 0xc0004d5d18?}) /home/wxh/.local/go/src/bufio/bufio.go:237 +0x1bb io.ReadAtLeast({0x7c3760, 0xc0001af1a0}, {0xc0001aad60, 0x9, 0x9}, 0x9) /home/wxh/.local/go/src/io/io.go:332 +0x9a io.ReadFull(...) /home/wxh/.local/go/src/io/io.go:351 net/http.http2readFrameHeader({0xc0001aad60?, 0x9?, 0xc0004d5df0?}, {0x7c3760?, 0xc0001af1a0?}) /home/wxh/.local/go/src/net/http/h2_bundle.go:1565 +0x6e net/http.(*http2Framer).ReadFrame(0xc0001aad20) /home/wxh/.local/go/src/net/http/h2_bundle.go:1829 +0x95 net/http.(*http2clientConnReadLoop).run(0xc0004d5f98) /home/wxh/.local/go/src/net/http/h2_bundle.go:8875 +0x130 net/http.(*http2ClientConn).readLoop(0xc00009e180) /home/wxh/.local/go/src/net/http/h2_bundle.go:8771 +0x6f created by net/http.(*http2Transport).newClientConn /home/wxh/.local/go/src/net/http/h2_bundle.go:7478 +0xaaa Goroutine 37 in state IO wait, with internal/poll.runtime_pollWait on top of the stack: goroutine 37 [IO wait]: internal/poll.runtime_pollWait(0x7f945c1e02a8, 0x72) /home/wxh/.local/go/src/runtime/netpoll.go:305 +0x89 internal/poll.(*pollDesc).wait(0xc0003ca000?, 0xc000202000?, 0x0) /home/wxh/.local/go/src/internal/poll/fd_poll_runtime.go:84 +0x32 internal/poll.(*pollDesc).waitRead(...) /home/wxh/.local/go/src/internal/poll/fd_poll_runtime.go:89 internal/poll.(*FD).Read(0xc0003ca000, {0xc000202000, 0x1300, 0x1300}) /home/wxh/.local/go/src/internal/poll/fd_unix.go:167 +0x25a net.(*netFD).Read(0xc0003ca000, {0xc000202000?, 0xc0004e6798?, 0xc0004c0808?}) /home/wxh/.local/go/src/net/fd_posix.go:55 +0x29 net.(*conn).Read(0xc000014028, {0xc000202000?, 0xc000136630?, 0x2c?}) /home/wxh/.local/go/src/net/net.go:183 +0x45 crypto/tls.(*atLeastReader).Read(0xc000276288, {0xc000202000?, 0x0?, 0x150fbb8ccb566149?}) /home/wxh/.local/go/src/crypto/tls/conn.go:787 +0x3d bytes.(*Buffer).ReadFrom(0xc0000a0978, {0x7c3860, 0xc000276288}) /home/wxh/.local/go/src/bytes/buffer.go:202 +0x98 crypto/tls.(*Conn).readFromUntil(0xc0000a0700, {0x7c3b80?, 0xc000014028}, 0xc0004cc2c0?) /home/wxh/.local/go/src/crypto/tls/conn.go:809 +0xe5 crypto/tls.(*Conn).readRecordOrCCS(0xc0000a0700, 0x0) /home/wxh/.local/go/src/crypto/tls/conn.go:616 +0x116 crypto/tls.(*Conn).readRecord(...) /home/wxh/.local/go/src/crypto/tls/conn.go:582 crypto/tls.(*Conn).Read(0xc0000a0700, {0xc00023c000, 0x1000, 0x11?}) /home/wxh/.local/go/src/crypto/tls/conn.go:1287 +0x16f bufio.(*Reader).Read(0xc00022a2a0, {0xc00020e2e0, 0x9, 0xc0004c0d18?}) /home/wxh/.local/go/src/bufio/bufio.go:237 +0x1bb io.ReadAtLeast({0x7c3760, 0xc00022a2a0}, {0xc00020e2e0, 0x9, 0x9}, 0x9) /home/wxh/.local/go/src/io/io.go:332 +0x9a io.ReadFull(...) /home/wxh/.local/go/src/io/io.go:351 net/http.http2readFrameHeader({0xc00020e2e0?, 0x9?, 0xc0004c0df0?}, {0x7c3760?, 0xc00022a2a0?}) /home/wxh/.local/go/src/net/http/h2_bundle.go:1565 +0x6e net/http.(*http2Framer).ReadFrame(0xc00020e2a0) /home/wxh/.local/go/src/net/http/h2_bundle.go:1829 +0x95 net/http.(*http2clientConnReadLoop).run(0xc0004c0f98) /home/wxh/.local/go/src/net/http/h2_bundle.go:8875 +0x130 net/http.(*http2ClientConn).readLoop(0xc00019e300) /home/wxh/.local/go/src/net/http/h2_bundle.go:8771 +0x6f created by net/http.(*http2Transport).newClientConn /home/wxh/.local/go/src/net/http/h2_bundle.go:7478 +0xaaa ] FAIL exit status 1
Does anyone know how to solve this problem?
Thanks!
In Go,http.ClientusesTransport(http.RoundTripperinterface).http.Transportis its default implementation. The defaulthttp.Transfermaintains a connection pool that holds connections that remain active or idle for some reason.
Basically all you need to do is make sure there are no connections in the pool*when you callgoleak.Verify
This can be done by:
client := http.Client{Transport: &http.Transport{DisableKeepAlive: true}}client.CloseIdleConnections()// Available since Go 1.12The above is the detailed content of Goroutine leaks when trying `ReadAll(response.Body)` where `response` is returned by http `client.Do(...)`. For more information, please follow other related articles on the PHP Chinese website!
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